Friction gearing



Oct. 20; 1931. D. JONES FRICTIO'N GERING Filed sept. 2s, 192e Naim. m LIMQ" .n v

. l@ 3mm/Wim. @Mu/b Stroh/W I i* friction `gearing ma e inated. Afurther o ject of my invention is.

Patented Oct. 20, 1931 PATENT LoFi-Ica UNITED! STATES PENNSYLVANIA,ASSIGNR T0 THE SHABPLES LEO n. Jonas, or rnmmmrma,

r DELAWARE FRICTION GEABING Application tiled September 28, 1926. SerialNo. 188,148.

Myv invention relates to an improvement in friction gearing and has forits object the provision of friction gearing in which wear on thecontacting friction surfaces is reduced to a minimum and inwhichvibration.is eifectual'ly eliminated at all speeds.

In friction gearing,

driven member of small diameter, the ictionally engaging surfacesthrough which force is transmitted are in contactl throughout only asmall area, such area being theoretically a mere line contact andbeingpractically not substantially greater than a line contact. Inconsequence slipping of the contacting surfaces upon one another resultsin uneven wear producing irregularity of the contacting surfaces of thegears,

In riction gearingfthe use of ra resilient device, such as a spring orweight, for maintaining the friction gears in contact has someadvantages but has heretofore produced vibration of the friction ears,particularly when the surface speed o the ears is high. When the gearsare vibrating t ere is undesirable interruption of contact, or variationof contact-pressure, between the contacting surfaces of the gears.

An object of my invention is to provide friction gearing in whichvariation in the relative speeds of rotation ofthe driving and drivenmembers may occur without causing wear on the contacting surfaces of thefriction gears.

vibration, that limits the speed at which be operated, is elimto providefriction gear'in inl which the relative speeds of rotation o the drivingand driven members lmay vary without the oc' currenceof slip in betweentheI contacting two additional frictionsurfaces also between.

surfaces of the rict1on gears.

In the practice of myl invention I provide between the driving` anddriven members contadting speed change that is desired and I provide thedriving and driven members and preferably between the driving member'and the and particularly in friction gearing' that includes a drivmgorl e Another ob]ect of my hinvention is to provide friction gearing inwhich friction gears that will produce the friction vgear associatedtherewith. The power that -is being transmitted is delivered from one ofsuch additional friction surfaces to the other and such additionalfriction surfaces are s o designed with respect to form or with respectto material or in both respects that slipping of one of such additionalsurfaces upon the other will not produce in jurious wear and will occurbetween such additional surfaces rather than between the contactingsurfaces of the friction gears them. selves. In the practice of myinvention a` spring or weight or other resilient meansthat wouldordinarily produce undesirable vibravtion may nevertheless be used tomaintain the friction gears in engagement and in the best practice of myinvention the same spring or weight or other resilient means is employedto maintain the second or additional pair of friction surfaces inengagement; and furthermore, in the practice of my invention the actionof such spring or weight or other resilient means may be so controlledas to elimif nate vibration of the friction gears. When the same` springor weight or other resilient means is employed to hold in engagement thefriction gears and also the second lor additional pairof frictionsurfaces, the force holding the friction gears in contact will be thesame as the force holding the second or additional pair of frictionsurfaces in contact. 1Under these circumstances, if the coeiiicient offriction betwen the friction gears is the same as the coeiiicient offriction between the second or additional pair of friction surfaces,slipping may be made to occur in accordance with my invention betweenthe second or additional pair of friction surfaces, instead of occurringbetween the friction gears, merely by making the torque arm of thesecond or additional friction surfaces less f than the torque arm of thefriction gear that is rotating therewith. Under these conditions theforce transmitted from one of the second or additional friction surfacesto the other will be greater than the actual'force transmitted by thefriction gear that isrotating with one of the second or additionalfriction surfaces.

aiy

the second or additional frictionsurfaces rather than between thefriction gears when the coefficient' of friction between the two pairsof friction surfaces is the same and the I secondor additional frictionsurface has a lesser torque arm than the friction gear to which thatadditional surface is connected.

In one'embodiment of my invention the friction gearing may consist offriction gears in frictional engagement and apower transmitting member.Only one of such gears will be directly connected to a main. driving ordriven member, preferably the latter, and thef power transmitting memberwill be connected to or carried by the other main driving or drivenmember, preferably theformer. The power transmitting member andthe gearthat is free of or not directly connected to either main driving orydriven member will respectively be provided with cooperating frictionsurfaces constituting an additional or second pair of friction surfacesthat are of such material and form as to resist wear or to wear evenlyor be uninjured thereby, e. g., such additional surfaces may be atcircular or ring-like surfaces in face contact. The coeiiicient offriction between the engaging surfaces of the gears and between theadditional friction surfaces will be so selected and the effectivetorque arm of the additional friction surfaces and of the friction gearthat rotates with oneof the additional friction surfaces will be soproportioned, and the force with which the two pairs of frictionsurfaces are brought into contact will be so regulated that slippingwill occur between the additional frictional surfaces rather thanbetween the gear surfaces. For example, if the two pairs of frictionsurfaces are held in contact by the same force, as in the embodiment ofmy invention herein specifically described for purposes of illustration,and the coeiiicient of friction between the additional friction surfacesis not greater than the coefficient of friction between the gearsurfaces, slipping will occur between the additional friction surfaceswhen the torque arm of one of the additional friction surfaces is lessthan the torque arm of the friction gear surface rotat-ing therewith orcarried thereby. Friction gearing embodying my invention may also beconsidered as a friction gear connected to one main shaft, a frictiondisk connected to the other shaft and an intermediate member, free ofboth shafts and having friction surfaces engaged respectively by saidgear and disk. Y

In other embodiments of my invention the coefficient of friction betweenthe two pairs of friction surfaces may not be the same but theadditional friction surfaces will never- Itheless be of such material ordesign'that they will resistor be uninjured by wear flaageaiy of such`design, for-example, with respect to torque arms, that slipping 4willoccur 4between such additional riction surfaces bel fore it occursbetween the surfaces vof the friction gears themselves.` i i yIn thepractice of my lnvention the fricl tion gears, and preferably also theadditional frictlon surfaces, areheld in Contact by resilient meansproducing the desired contacting force, the two pairs of surfacespreferably being held in contact by the same means. But the action. ofthat resilient contacting means is so damped or otherwise controlledthat vibration that ordinarily results fromv drawing which shows, partlyin elevation v and partly in cross section, friction gearingconstituting one illustrative embodiment of my invention. i

Referring to the drawin one member, preferably the driving mem er,comprising the shaft 1 is supported in bearings 2 and 3 and may hav'emounted upon it any desired driving device such as the pulley 5. Afriction disk 6 is mounted upon the shaft 1 and suitably held in placethereon as by set screws or will wear evenly, and the gearing will be l7 and 8. The friction disk 6 is provided with i a hub 9 upon which anintermediate friction disk 10 is mounted for rotation. The hub 11 of theintermediate disk 10 is preferably provided with a bearing such as aBabbit metall bushing 12. Intermediate friction disk 10 is provided witha friction face such as a ring or circular band of friction material 27of any suitable character that may be held in place in any manner as bybeing cemented to the disk 10. If desired the friction material 27 maybe placed within a shoulder 28 as shown. The ring of friction material27 is shown as having a diameter not greater than the diameter of thefriction disk 6. Also on the face of the intermediate disk 10 a secondcircular face of friction material 14 is mounted as by being located ina groove in a face of the disk as shown. The rings 14 andv 27 offrictional material are preferably, but not necessarily, located onopposite faces, as shown, ofthe disk 10. The other member of thefriction gearing, which may be either the driving or driven member mayconsist of a shaft 16 mounted in a bearingl 17. A friction wheel 15 ismounted upon the shaft 16 and frictionally engages the ring of frictionmaterial 14. v

`respect to their coe-flicients of friction that anyv slipping willoccur under these conditions at the point where the greatest force mustbe transmitted by friction, namely, on the ring of friction material 27which is flat and is in contact with the flat face of the friction disk6. It is thus apparent that slipping that would occur in ordinaryfriction gearing between the ringfof friction material 14 and thefriction wheel 15 will be eliminated and that necessary or desiredslipping will occur between dat surfaces that will resist wear or willnot be injured thereby and will wear evenly. v

For the purpose of holding the friction gears in contact a resilientforce is highly advantageous, particularl in friction gearing of the tye above descri edl wherein the gearing may e operated at very highspeeds but in previous constructions unavoida le irregularities of thesurfaces of the friction gears cause excessive vibration particularlywhen resilient force is so employed. In accordfance with my inventionthe force holding the friction gears in Contact is produced by resilientmeans and the same force is preferably employed to hold the additionalfrlction surfaces in contact. But, that force is so damped or controlledthat vibration is reduced to harmless proportions or does not occur,such damping preferably being caused b the force itself. If contact-bebroken or ifY the force .of contact. be reduced between the frictiondisk andthe friction wheel in previous constructions, particularly thoseemploying resilient contact means, there is in effect a hammer blowbetween the parts when operative lconditions are restored;andunnecessarily large loads will be imposed .upon the bearings withresulting noise and the probable development of ripples on the frictionsurfaces. To this end my invention includes resilient means for holdingthe fric,-

. tion surfaces in frictional engagement and damping means whereby theresilience of such resilient means will be prevented from causingserious vibration. To accomplish ythis object of my invention a casingorlslideway 21 is provlded which may be mounted upon the bearing 2 as bybolts 29; and means g for applying a resilient force to the bearing pin18 of the shaft 1, and thus to the friction surfaces, and means fordamping'that resilient force are carried by casing or slidewayV 21.-

Within the casing or slideway 21 is slidably mounted plunger 2Q that hasa groove 23y within Whlch acts pin 22to prevent rotation ball 19, theball 19 engaging the bearing pin- 18. A second plunger 20 is locatedwlthin the casing or slideway 21 and the faces 26 of the plungers 20 and20 are in engagement.

'Spring 24 engages the outer end of the plunger 20 and its tension isadjusted by means of screw plug `25 that is locked in position by thenut 25. The tension of spring 24 holds both;

pairs of friction surfaces in contact under the same pressure.Theengaging faces 26 of the plungers 20 and 20 are made oblique to theaxis of the plungers and the compression of spring 24 causesthe'plungers 2U and 20 to bind slight-ly within the casing or slideway21. Thus any impulse tending to start vibration is damped in bothdirections and the damping eect may be increased by decreasing the anglebetween the contacting faces 26 and the axis of the plungers 2() and 20.If a great enough shock occurs between the friction material 14 and thefriction wheel 15 to cause the contacting surfaces of those parts toseparate, the friction disk 10 will vmove up slowly toward the frictionwheel 15 instead of bringing the friction material 14 into engagementwith the friction wheel 15 with a shock.

In the particular embodiment of my invention illustrated and abovedescribed the force that is damped also produces a kdamping action ofthat force that is proportional to the angle and coefficient of frictionbetween the contacting faces 26 andbetween the plungers 20 and 20 andslideway 26 and the damping effect can never defeat the contactingeffect tween them, and th'e speed of the driven vmember drops behindthat of the driving member during such disengagement or reduction of'contacting pressure, slipping will occur between the fiat surface ofthedisk and the flat surface of the friction material 27, and not betweenthe friction material 14 and the wheel 15, while the parts are beingbrought up to speed.

In the operation of a centrifuge, which is animportant application of mylnvention, my friction gearing may be so designed that a force of sixpounds is transmitted by friction between the friction wheel 15`and thefriction surface 14. In order to transmit this force the surface of thegears maybe brought together with a pressure of approximately twentypounds, a greater pressure being undesirable because 1t would leadtowear and vibration and unduly increase the thrust in the thrust bearingand the radial pressure in the bearings of the high speed shaft. The

tween the fiat friction surfaces and will notI result in wear of thefriction wheel. If an electric motor is used to drive the low speedshaft such motor Willexert greater torque at starting and at speedsbelow normal speed, perhaps a torque that would require transmitting aforce of sixty pounds at the point of contact between the frictiongears. It is undesirable to employ a contacting force high" enough toprevent slippage under these conditions. It is, however, undesirable tohave slippage between the friction gears, the surface of at least one ofwhich is curved. On

the other hand it is desirable to have the motor come up to speed assoon as possible. In the practice-of my invention such excessivestarting torque will result only in slippage between flat surfaces andno harm will be done and the desirable speed of the motor will 'bequickly attained. Furthermore, if bearings lock or bind the resultingslippage will result only in a relative movement of the flat frictionsurfaces. v

While I have described a preferable form of my invention withconsiderable detail I do not intend that I shall be limited to theparticular form shown or to the details thereof; but intend that myinvention shall include such modifications and variations as fall withinthe hereunto appended claims. In this connection it is to be noted thatthe casing 21 which is primarily a guide for the plungers 20 and 20 maybe of any form so long as pressure of the plungers 2() and 20 againsteach other will produce a binding action bey, tween the plungers andtheir guide or casing or slideway; and it isobvious that the plungersmay be of any form and that they might each consist of several parts solong as pressure between them comes upon oblique surfaces and causes abinding action between the plungers and their guide or casing. It isalso to be noted that in friction gearing embodying my invention poweris transmitted from a driving shaft to a driven shaft by being passedthrough 2 pairs of friction surfacesthat are arranged in series in thesense that the power is first transmitted from a friction surface of'one pair of surfaces to the other friction surface of that pair and thenpassed from a friction surface of the second pair of surfaces to theother friction surface of .that4 pair.

What I claim as new and desire to secure by Letters Patent is: p

1. In friction gearing, a driving member, a driven member, two pairs offrictionally engaging power transmitting surfaces arranged in seriesrelation for transmitting power Vfrom said driving member to said drivenmember, one of said pairs of surfaces beingA capable of transmittingmore power by friction .than the other, and

a single damped means acting to hold said pairs of surfaces in contact.'

V2. In friction gearing, a first pairof power transmitting frictionsurfaces in rolling contact, a second pair of power transmittin planefriction surfaces in face contact an arranged in series relation withsaid first pair of friction surfaces, said first pair of frictionsurfaces being capable of transmitting more power by friction than saidsecond pair of friction surfaces, and a single resilient means acting tohold said pairs of surfaces in contact.

3. In friction gearing, a first pair of power transmitting frictionsurfaces in rolling contact, and a second pair of power transmittingplane friction surfaces in face contact and arranged in seri es relationwith said first pair of friction surfaces, and said surfaces in facecontact being adapted always to slip without transmitting great enoughpower to cause slipping of said surfaces lin rolling contact.

4. In friction gearing, a first pair of power transmitting frictionsurfaces in rolling contact, and a second pair of power transmittingfriction surfaces in face Contact and arranged in series relation withsaid first pair offriction surfaces, a single resilientmeans for holdingsaid pairs of surfaces in contact, and damping means for said resilientmeans and actuated by the force thereof.

5. In friction gearing, a first pair of power transmitting frictionsurfaces in rolling contact, and a second pair of power transmittingfriction surfaces in face contact and arranged in series relation withsaid rst pair of friction surfaces, and a single self-dampingresiliently actuated means for contacting said pairs of surfaces.

6. In friction gearing, first and second members in frictionalengagement, a power transmitting member frictionally engaging said firstmember, with a coefficient of friction less than or substantially equalto that between said first and second members, at a point thereofradially inward of the point at which said first member engages saidsecond member, resilient means holding said first and second membersandy said power' transmitting member in frictional engagement, andmeansfor damping movement of said first and second members toward andfrom each other. y

7. In friction gearing, a friction wheel, a

and a guide engaging said contacting members and holding them coaxialtherewith.

9. In friction gearing, first and second members infrictionalengagement, a spring for holding said members in engagement, a guide,and means within the guide and engaging said first member and engaged bysaid spring for spreading into frictional engagement with said guideunder compression between said spring and said first member.

10. Means for bringingv members' of friction gearing into contact witheach other comprising a guide, plungers within the guide and therebyheld coaxial therewith and contacting at surfaces oblique to the axisthereof,

one of said plungers being adapted to engage i one of the members ofsaid gearing, and a spring engaging the other of said plungers.

11. In frlction gearing an axially movable intermediate disk, a frictionwheel engaging one surface of saiddisk, a power transmltting memberfrictionally engaging the other surfaceof said disk, a spring -forpressing said .transmitting member toward said disk, and damping meansbetween the said spring and transmitting member.

12. In friction gearing, first and. second p members in frictionalengagement, means for resiliently moving'- the first of said membersinto frictional engagement with Ithe second of i said members, and meansfor damping'the movement of the first of said members from and towardthe second `of said members. f f

13. In friction gearing, frictiony members V50-mounted for rotation,onesof which is movy able -into contact with the other, and selfname tothis specification.

ing the other of said contacting members,

plungers in said guide and thereby held co.- i axial therewith havingoblique contacting surfaces, one of said plungers engaging one of saidmembers, and resillent means engaging the other of said plungersfor'maintain- 7 ing said members in frictional engagement.

In testimony whereof, I have signed my LEO D. JONES.

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damping resiliently 'actuated means for moving said last named memberinto contact withJ the other of said members. C

55 14. In friction gearing, first andJ second membersin frictionalengagement, means for resiliently moving the first of said members intofrictional engagement with the second of said members, and means fordamping the 80 movement of the first of said members from and toward thesecond of said members with a force proportional to that tending tocause such movement.

15. In friction gearing, a pair4 of members 65 in frictional engagement,a guide, a pair of

